Investments - Net Investment Income (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Net Investment Income [Line Items]
Gross investment income	$ 205.0	$ 117.0
External investment expense	(1.2)	(0.4)
Net investment income	203.8	116.6
Total fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	177.3	98.3
Equity securities
Net Investment Income [Line Items]
Gross investment income	7.6	5.4
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	15.0	7.3
Policy loans
Net Investment Income [Line Items]
Gross investment income	1.1	1.2
Other invested assets
Net Investment Income [Line Items]
Gross investment income	$ 4.0	$ 4.8

Amount, before investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

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Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

+ References

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